Charges Of Opposite Polarity Research Articles

Dynamic bipolar charge recombination model for electroluminescence in polymer based insulation during electrical tree initiation

A dynamic bipolar charge recombination model is proposed to explain the charge injection and electroluminescent behaviour found experimentally in pin-plane polymeric resin samples under high alternating voltage stress. The model is described for two electrode geometries producing parallel and divergent electric fields. The long term rise in electroluminescence intensity at constant alternating stressing voltage is accounted for by charge trapping in the polymer close to the electrode and recombination via mobile charge recombining with trapped charge of opposite polarity. The phase profile of the electroluminescence is a consequence of charge injection across a potential barrier and field limiting behaviour occurring at the injection electrode. The saturation electric field under field limiting conditions and the injected current density as a function of time can be calculated from the experimental conditions and knowledge of the charge injection law. Field limiting behaviour provides a feedback mechanism that maintains net charge neutrality within the resin over time.

EFFECT OF LOADING WITH AIM OIL AEROSOL ON THE COLLECTION EFFICIENCY OF AN ELECTRET FILTER

ABSTRACT Loading of an electret filter changes the distribution of electrical field in the filter from its preloading condition, and, therefore, affects the filtration efficiency of the filter. Liquid droplets collected on electret filters cause degradation of the electrostatic enhancement of filtration efficiency because of charge neutralization and the formation of a dielectric coating over die charged fibers. In this study, calculations were made for the penetration of aerosol particles through a spun-type electret filter as a function of the particulate loading. An assumption was made that each charge collected neutralized one charge of opposite polarity on the fibers of the filter. It was also assumed that the electrostatic charges present on the particles followed the Boltzmann equilibrium charge distribution. The decrease in fiber charge and resulting increase in penetration were calculated as a function of time and of total particulate loading on the filter. The calculated penetrations were compar...

Combined electrostatic objective and emission lenses for microcharacterization of surfaces

It is shown how the matrix-transfer method can be used to treat electrostatic particle-optical assemblies for finding solutions where a collimated beam of charged primary particles is focused on a flat sample surface, while at the same time charged secondary particles emitted with low energy from the surface as a consequence of the primary particle bombardment are guided backward through the assembly to form a well collimated beam suitable for further handling. Examples of solutions are presented for primary and secondary particles of equal and opposite charge polarity.